The invention relates generally to the field of pulmonary drug delivery. More specifically, the invention relates to dry powder dispersion devices and methods for dispersing dry powder medicaments for inhalation by a patient.
Pulmonary drug delivery is becoming a promising way to deliver drugs to a patient. Pulmonary drug delivery relies on inhalation of a drug dispersion or an aerosol by the patient so that the active drug within the dispersion can reach the distal (alveolar) regions of the lung. It has been found that certain drugs are readily absorbed through the alveolar regions directly into blood circulation. For example, pulmonary delivery is particularly promising for the delivery of proteins and polypeptides which are difficult to deliver by other routes of administration. Such pulmonary delivery is effective both for systemic delivery and for localized delivery to treat diseases of the lungs.
A variety of approaches have been proposed to achieve pulmonary drug delivery. Such approaches include the use of liquid nebulizers, metered dose inhalers (MDI""s) and dry powder dispersion devices. Of these approaches, dry powder dispersion devices are of particular interest. Exemplary embodiments of such dry powder dispersion devices are described in U.S. Pat. No. 5,740,794 and Ser. No. 08/309,691, filed Sep. 21, 1994, the complete disclosures of which are herein incorporated by reference. These patents describe hand-held powder dispersion devices which extract powder from a receptacle and aerosolize the powder so that the aerosolized powder may be inhaled by a patient. Such dry powder dispersion devices have proven to be tremendously successful in adequately aerosolizing dry powders for subsequent inhalation.
Even so, it would be desirable to provide various enhancements to increase the marketability, ease of use, functionality, and other features of such dry powder dispersion devices. Hence, it is an object of the invention to provide improved dry powder dispersion devices and methods for their use.
The invention provides exemplary systems, apparatus and methods for aerosolizing a powdered medicament. One exemplary apparatus of the invention comprises a pressurization cylinder and a piston that is slidable within the cylinder to pressurize a gas within the cylinder. A handle is coupled to the cylinder and is movable between an extended position and a home or retracted position to pressurize the gas within the cylinder. An aerosolizing mechanism is further provided to aerosolize a powdered medicament that is held within a receptacle using pressurized gas from the cylinder. A carriage assembly is provided to receive the receptacle and to couple the receptacle to the aerosolizing mechanism so that the powder may be extracted from the receptacle and aerosolized. The apparatus further includes a first and a second interlock which may be operated to engage the carriage assembly, thereby preventing coupling of the receptacle with the aerosolizing mechanism. The first interlock is released to allow movement of the carriage when the handle is moved to the fully extended position. The second interlock becomes engaged with the carriage when the receptacle is only partially inserted into the carriage assembly.
With such a configuration, the apparatus is operated to aerosolize the powdered medicament by inserting the receptacle into the carriage assembly to a fully loaded position to ensure that the second interlock is not engaged with the carriage assembly. The handle is then extended to a fully extended position and retracted back to the home position to produce a charge of pressurized gas and to release the first interlock from the carriage assembly. A fire button on the apparatus is then operated to move the carriage assembly toward the aerosolizing mechanism until the receptacle is coupled with the aerosolizing mechanism. Upon coupling of the aerosolizing mechanism, the charge of pressurized gas is released to aerosolize the powdered medicament that is held within the receptacle.
Such a configuration is advantageous in that the aerosolizing apparatus may not be operated if the receptacle is not fully inserted and the handle is not fully extended. In this way, controls are provided to ensure correct operation of the aerosolizion apparatus.
In one particularly preferable aspect, the receptacle has a front end, a back end, and a cavity which holds the medicament. The front end includes at least one notch, and the carriage assembly includes a key so that the receptacle may not be fully inserted into the carriage assembly if the notch does not mate with the key. In this way, the carriage assembly may not be operated to couple the receptacle with the aerosolizing mechanism if the notch does not mate with the key, thereby preventing full insertion of the receptacle into the carriage assembly.
In one particular aspect, the aerosolization apparatus further includes a sensor arm having a roller. The roller rolls over the cavity during insertion of the receptacle into the carriage assembly to move the sensor arm against the second interlock, thereby causing a latch on the second interlock to engage the carriage assembly until the roller rolls over the entire cavity. In this way, the latch will remain engaged with the carriage assembly to prevent its movement as long as the roller is in apposition to the cavity. Once fully inserted, the latch is released to allow operation of the carriage assembly. In still a further aspect, the sensor arm defines a well which receives the cavity when the receptacle is fully inserted. The well aligns the cavity with the aerosolizing mechanism to facilitate coupling of the receptacle to the aerosolizing mechanism.
In one particular aspect, the apparatus further includes a catch which engages the carriage assembly when the carriage assembly is moved to couple the receptacle to the aerosolizing mechanism. A release button is provided to release the carriage assembly from the catch. In this way, the carriage assembly will not accidentally be lowered to decouple the receptacle from the aerosolizing mechanism until the powdered medicament has been aerosolized. In another aspect, a valve is disposed in an airway between the cylinder and the aerosolizing mechanism. The valve has an open position and a closed position, and is generally in the closed (but unlocked) position during extension of the handle to the extended position. Such a configuration is advantageous in that the air employed to fill the cylinder is not drawn through the airway, thereby providing a cleaner supply of air to fill the cylinder.
In one particular embodiment, an aerosolizing apparatus is provided which comprises a housing, a pressurization cylinder, and a piston that is slidable within the cylinder to pressurize a gas within the cylinder. The piston is pivotally attached to the housing, and a handle is operably attached to both the housing and cylinder. The handle is operated to move the cylinder relative to the piston to pressurize a gas within the cylinder. An aerosolization mechanism is provided to receive gas from the cylinder to aerosolize a powdered medicament. Construction of the apparatus in this manner is advantageous in that the piston may pivot relative to the housing as the handle is operated. In this way, the piston remains generally aligned with the cylinder during operation of the handle, thereby facilitating operation of the handle and reducing wear between the components.
In one particular aspect, a linkage is disposed between the handle and the cylinder. The linkage is pivotally attached to the housing and the cylinder to further facilitate operation of the handle. In another aspect, the housing includes a top end and a bottom end, and the aerosolizing mechanism is disposed near the top end. Further, the piston is pivotally attached to the housing at the bottom end. Such a configuration is advantageous when a one-way check valve is disposed in the piston because the check valve will be disposed near the bottom end of the housing to reduce the chances of having any powder which may fall through the housing from accumulating on the check valve.
In a further embodiment, the invention provides an aerosolizing device which comprises a housing and a capture chamber which extends from the housing. An aerosolizing mechanism is disposed in the housing to introduce a powdered medicament into the capture chamber. The aerosolizing mechanism is provided with air channels which allow air to enter into the capture chamber when a patient inhales to extract the powdered medicament from the capture chamber. The aerosolizing mechanism farther includes a structure to distribute air entering into the capture chamber through the air channels such that the powdered medicament is removed from the capture chamber as a bolus that is substantially unmixed with the entering air.
Such a device is operated by dispersing the powdered medicament into the capture chamber and then inhaling from the capture chamber to extract the powdered medicament. Air is allowed to enter into the capture chamber through the air channels in a manner such that substantially none of the incoming air mixes with the powdered medicament to allow the medicament to be removed as a bolus. Hence, by introducing the air in this manner, the air serves as a piston to uniformly lift the aerosolized powder up through the capture chamber where it is inhaled by the patient.
In one particular aspect, the capture chamber has a geometric center and the aerosolizing mechanism is offset from the center because of the inclusion of other component parts within the housing. The structure is fashioned to distribute more air to regions of the capture chamber which are more remote from the geometric center. In this way, the remotest regions of the capture chamber will receive more air so that substantially no mixing of the powdered medicament occurs as air is drawn into the capture chamber during inhalation by the patient. In another aspect, the structure comprises a curved flange member and serves to channel some of the air radially outward as it enters into the capture chamber.
In one particularly preferable aspect, the aerosolizing mechanism includes a cylindrical passage or channel through which the powdered medicament passes to reach the capture chamber. The top end of the housing is generally perpendicular to a distal end of the passage. In this way, as the powdered medicament enters into the capture chamber, it will tend to disperse evenly throughout the capture chamber. In yet another aspect, a flexible seal is coupled to the housing to provide a seal with the capture chamber. The flexible nature of the seal is advantageous in that the capture chamber may easily be slid over the housing without causing excessive wear to the seal.
In one particular embodiment, the invention provides a device for aerosolizing a powdered medicament which comprises a housing having at least one piercing element for piercing a hole in a receptacle that contains a powdered medicament. A core is insertable into the housing and has an extraction lumen or tube and at least one air channel. The air channel is aligned with the piercing element when the core is inserted into the housing to allow air to flow into the receptacle through the air channel. A source of pressurized gas is further provided to extract the powdered medicament through the extraction lumen when the extraction lumen is inserted into the receptacle. Use of the housing and core is advantageous in that the core may be manufactured with a relatively small cost and may be made disposable, while the housing which includes the piercing element may be re-used.